Cable connecting system

ABSTRACT

The cable connecting system comprises a contact body ( 28 ) having first means on the cable connecting end for producing a releasable electric or mechanical connection to the end of a cable ( 30 ) and is more particularly configured as a plug contact for enabling an electrical contact on a contact side. A reliable and reusable electrical and mechanical connection is achieved in said cable connecting system in that the clamping element is configured in the form of a clamping cone ( 21 ), the clamping contour ( 20 ) has a segment ( 20   a ) in which the limiting surface extends approximately parallel to the surface of the cone of the clamping cone ( 21 ) and in that the inner width (w) of the clamping sleeve ( 23 ) in the area of the clamping contour ( 20 ) is smaller than the maximum outer diameter of the clamping cone ( 21 ).

TECHNICAL FIELD

The present invention relates to the field of cable connectionstechnology. It relates to a cable connection system in accordance withthe precharacterizing clause of claim 1.

Such a cable connection system is known, for example, from the documentsU.S. Pat. No. 3,560,909 or U.S. Pat. No. 5,487,679 or DE-U1-201 19 531.

PRIOR ART

In order to fabricate cables having a conductor cross section of a fewmm² to a few 100 mm² which comprise a stranded wirestranded wiresurrounded by insulation such that they are connection-ready, contactelements in the form of cable shoes, plugs, sockets or the like areusually connected to the cable ends by the exposed stranded wirestrandedwire being inserted into a compression sleeve fitted on the contactelement and being mechanically and electrically connected to the contactelement by the sleeve being compressed. In order that the compressionproduces a permanent and electrically faultfree connection between thecompression sleeve and the stranded wire, the compression sleeve needsto be dimensioned correctly in terms of its inner and outer diameterwith respect to the stranded wire cross section. Since, owing to itsfunction, the compression sleeve is often made from a different materialthan the contact element, it is connected to the contact element bymeans of a connection technique such as soldering, bonding or welding,usually by means of welding. Furthermore, the compression sleeve needsto be properly annealed in order to have the material propertiesrequired for the compression operation. Furthermore, a specialcompression swage (crimping tool, crimping insert etc.) which has thecorrect geometry and is correctly dimensioned is required forcompressing the compression sleeve with the stranded wire.

Since the cable fabrication by means of compression sleeves iscomplicated and laborious owing to the above-described circumstances andit is necessary to use special tools which need to be kept available onsite during fabrication, it has long been desired to simplify thefabrication process and to make this process possible without specialtools. Various proposals have already been made in the past involvingusing axial clamping screw connections for the purpose of fabricatingcables, which clamping screw connections can be actuated using normalfork wrenches.

U.S. Pat. No. 3,560,909 mentioned initially has disclosed a terminalconnector for a cable, in the case of which a thread section is arrangedon the rear end of a contact pin and becomes a conical point. A sleevehaving a corresponding inner thread can be screwed over the end of thecontact pin until the cone point hits the inner rim of a circularopening in the base of the sleeve. During fabrication, the exposedstranded wire of the cable is pushed partly through the opening into thesleeve. When the sleeve is screwed onto the end of the contact pin, theindividual wires of the stranded wire are forced away outwards by thecone point and are clamped between the cone point and the inner rim ofthe sleeve opening (FIG. 5). One disadvantage with this type of clampingis the fact that the edge-like rim of the sleeve opening presses intothe individual wires of the stranded wire so as to form a notch when thescrew connection is tightened and thus reduces the mechanical strengthof the individual wires.

U.S. Pat. No. 5,487,679 cited initially has disclosed a similarelectrical connector, in the case of which, instead of a cone point, apoint having a rounded first contour is inserted which presses againstthe inner wall of the sleeve with a second rounded contour. The contoursare designed such that the central opening angle of the point is greaterthan the opening angle of the sleeve. This results in a taperingclamping region for the stranded wire of the cable to be connected. Thepoint is made from a deformable metal such that the individual wires ofthe stranded wire press into the point when the connection is tightened.This solution has the disadvantage that, owing to the different contoursof the point and the sleeve, only a comparatively short region isavailable in which the actual clamping contact takes place, and whichcorresponds to the region of the indents in the point. A furtherdisadvantage is the plastic deformation of the point owing to theindividual wires pressing into it: the plastic deformation leads to thereduction of clamping forces such that the clamping connection caneasily lose its effectiveness. Furthermore, owing to the remainingdeformations of the point, the connector can only be used once or atmost a few times.

DE-U1-201 19 531, likewise cited initially, has disclosed an electricalcontact part having an axial clamping screw connection, in the case ofwhich either (FIG. 1) a contact point having a contour relating to U.S.Pat. No. 5,487,679—similar to as in U.S. Pat. No. 3,560,909—is pressedagainst the inner edge of a sleeve opening and thus forms a notch in theindividual wires of the cable stranded wire, or (FIG. 2) a conical pointcan be moved through a sleeve opening having a rounded rim contour, withplay. In the lastmentioned embodiment, the individual wires of thestranded wire are pinched in a frictional manner between the point andthe rim of the sleeve opening, which in turn leads to mechanicalweakening of the individual wires.

Finally, EP-B1-0 875 961 (FIG. 1) has disclosed so-called axial screwclamps, in the case of which a clamping element, which can be screwedinto a hollow-cylindrical housing, having a conical point can be screwedagainst a clamping contour arranged in the interior of the housing.Since in this case the clamping element is formed as a separate partwithout any connection to the contact side by means of techniques suchas soldering, bonding or welding, there is an unfavorable currentdistribution primarily at high currents. Furthermore, the screwconnection to be operated from the inside is complicated in terms ofmanipulation and prevents, for example, simple tightening of theclamping screw connection.

SUMMARY OF THE INVENTION

One object of the invention is therefore to provide a cable connectionsystem which avoids the disadvantages of known systems and isdistinguished in particular by a permanent, good electrical contact anda high mechanical strength of the connection and by simple manipulationwithout the need for special tools.

The object is achieved by the entirety of the features in claim 1. Theessence of the invention consists in the clamping element being in theform of a clamping cone, the clamping contour comprising a section inwhich the limiting face extends approximately parallel to the cone faceof the clamping cone, and the clear width of the clamping sleeve in theregion of the clamping contour being smaller than the maximum outerdiameter of the clamping cone. Owing to the particular design of theclamping zone, gentle, large-area clamping of the stranded wire isbrought about which is distinguished by having a high mechanicalclamping and retaining force, provides a large electrical contact areafor current transmission purposes and reliably avoids notching effectson the stranded wire and associated damage. The limiting face of theclamping contour in the first section can in this case optionally extendparallel to the cone face of the clamping cone or, if it is intendedthat mechanical fine-wire and very fine-wire conductors be clampedparticularly gently, can have a slightly (convexly) rounded sectionwhich extends on average approximately parallel to the cone face of theclamping cone.

One preferred refinement of the cable connection system according to theinvention is characterized in that a thread region is arranged on thatside of the clamping cone which faces away from the cable, for thepurpose of screwing on the clamping sleeve, and in that a first recessis provided between the thread region and the clamping cone for thepurpose of accommodating the stranded wire. This prevents, in a simplemanner, the stranded wire from protruding into the thread region whenthe connection is mounted and impeding the screw connection of thecontact body and the clamping sleeve there.

Another preferred refinement of the cable connection system according tothe invention is characterized in that at least one viewing hole isprovided in the clamping sleeve, it being possible to visually check theinsertion of the stranded wire into the clamping zone between theclamping cone and the clamping contour through said viewing hole. Thismakes it possible to ensure, without any particular complexity, that thestranded wire of the cable to be connected is introduced or insertedinto the clamping zone in the proper manner and thus makes possible astable and functionally reliable screw connection. It is madeparticularly easy to visually check the insertion despite the differentrotary position of the clamping sleeve if two opposite viewing holes areprovided in the clamping sleeve.

In order that the clamping zone can be prepared in optimum fashion forthe insertion of the stranded wire, it is advantageous if, in accordancewith another refinement of the invention, a marker recess is arranged onthat side of the clamping cone which faces away from the cable, it beingnecessary for the clamping sleeve to be screwed onto the contact body upto this marker recess before the stranded wire of the cable is insertedinto the clamping zone between the clamping cone and the clampingcontour. However, other markers can also be provided to the same effect,instead of the marker recess.

Further embodiments are described in the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

The invention will be explained in more detail below with reference toexemplary embodiments in connection with the drawing, in which:

FIG. 1 shows a partially longitudinally sectioned illustration of afirst exemplary embodiment of a cable connection system according to theinvention which is designed for a conductor cross section of 50-70 mm²and in which the contact side is in the form of a socket;

FIG. 2 shows a perspective side view of the cable connection systemshown in FIG. 1;

FIG. 3 shows a longitudinal section of an exemplary embodiment,comparable to that in FIG. 1, of the cable connection system accordingto the invention during fabrication; the clamping sleeve is screwed onup to a marker recess in order that the stranded wire of the cable to beconnected can be inserted into the clamping screw connection in anoptimum manner;

FIG. 4 shows one exemplary embodiment of the invention for line crosssections of 25-35 mm², in which the contact side is in the form of aplug;

FIG. 5 shows one exemplary embodiment of the invention for line crosssections of 25-35 mm², in which the contact side is in the form of asocket; and

FIG. 6 shows one exemplary embodiment, comparable to that in FIG. 3, inwhich the clamping contour for mechanically sensitive, fine-wire or veryfine-wire conductors has a rounded section opposite the clamping cone.

APPROACHES TO IMPLEMENTATION OF THE INVENTION

FIG. 1 shows a partially longitudinally sectioned illustration of afirst exemplary embodiment of a cable connection system according to theinvention which is designed for a conductor cross section of 50-70 mm²and in which the contact side is in the form of a socket. However,express reference should be made at this point to the fact that thesolution according to the invention can be used up to the greatestconductor cross sections available on the market. FIG. 2 shows aperspective side view. The cable connection system shown in FIGS. 1 and2 comprises a socket 10 having an essentially cylindrical socket body 11extending along an axis 33 (FIG. 3). The socket body 11 has a hole atthe left-hand end for the purpose of accommodating a plug pin (notshown), in which an annular contact lamination 12 is arranged for thepurpose of making defined contact. A spring bolt 13, which can be pushedback counter to the pressure of a compression spring 15, is held at theend of the hole for the purpose of accommodating the plug pin by meansof a screwed-in perforated nut 14. An O ring 16 is arranged on theoutside of the socket body 11 at the level of the perforated nut 14 forthe purpose of sealing the plug connection.

A thread region 18, which is provided with an outer thread and extendsup to a first recess 19, adjoins the right-hand end of the socket body11. Behind the first recess 19, the socket body 11 becomes a clampingcone 21, which runs to a point towards the end. A second recess 27,which is used as the marker recess, is provided in the center of thethread region 18. A clamping sleeve 23 can be screwed onto that end ofthe socket body 11 which is provided with the thread region 18 and theclamping cone 21. At one end the clamping sleeve 23 has an inner threadwhich fits the thread region 18. At the other end, a clamping contour 20is integrally formed on the inside. As shown in FIG. 3, the clampingcontour 20 has a first section 20 a which tapers in the form of a coneand is adjoined by a second section 20 b having a constant innerdiameter. The opening angle of the first section 20 a is the same as thecone angle of the clamping cone 21, with the result that the surfaces ofthe two elements extend parallel to one another. The clamping sleeve 23has a funnel-shaped opening 22, through which the stranded wire 29 of acable 30 can be inserted (FIG. 3). In each case a width across the flats17 or 25 (17′ in FIGS. 4, 5) is milled on the outside of the socket body11 and the clamping sleeve 23 such that the clamping connection 26comprising the clamping sleeve 23 and the clamping cone 21 can betightened in a defined and simple manner by means of fork wrenches orwith the aid of a torque wrench. Two opposite viewing holes 24 areprovided in the central region of the clamping sleeve, and the insertionof the stranded wire 29 during the fabrication process can be observedand visually checked through these viewing holes 24. The socket body 11and the clamping sleeve 23 are preferably made from brass and areprovided with a silver plating. The inner diameter of the second section20 b of the clamping contour 20 is approximately 12 mm—if the socket 10is designed for conductor cross sections of 50-70 mm².

FIG. 3 illustrates, in the manner of a snap shot, one step in thefabrication process which comprises several steps. For fabricationpurposes, initially the stranded wire 29 is exposed at the end of thecable 30 over a predetermined length by the insulation being removed.Then, the clamping screw connection is prepared for accommodating thestranded wire 29 by the clamping sleeve 23 being screwed onto thecontact body 28 up to the marker recess 27, as is illustrated in FIG. 3.If the clamping sleeve 23 is in the prescribed position, the strandedwire 29 is inserted along the axis 33 through the funnel-shaped opening22 in the clamping sleeve 23 and pushed in to such an extent that theindividual wires can easily be seen through the viewing holes 24 (FIG.3). If the clamping sleeve is now screwed on further, the individualwires of the stranded wire located between the clamping contour 20 andthe clamping cone 21 are carried along and remain visible in the viewingholes 24, if the screw connection has been performed properly. In thelast stage of the screw connection, the ends of the individual wires areaccommodated by the recess 19. The recess 19 makes sufficient spaceavailable for the individual wires not to penetrate into the threadregion 18 and impede the screw connection operation there.

The screw connection preferably takes place by means of a torque wrench,which is placed on the width across the flats 17 or 17′. Locking takesplace using a fork wrench on the width across the flats 25. The parallelorientation of the clamping faces of the clamping cone 21 and thesection 20 a of the clamping contour in conjunction with the diameterratios (clear width w of the clamping contour 20 smaller than themaximum outer diameter of the clamping cone 21) ensures that theindividual wires of the stranded wire 29 are subjected to a uniform loadover a large area. As a result, a high retaining force is achieved, onthe one hand, and, on the other hand, damage to the individual wires isreliably avoided. In addition, the edges of the section 20 a can berounded off in order to also rule out any notching effect there.

Two exemplary clamping screw connections for smaller conductor crosssections (25-35 mm²) are depicted in FIGS. 4 and 5, and these clampingscrew connections are designed in the clamping region in the same way asthe exemplary embodiment shown in FIG. 1. In the example in FIG. 4, thecontact body is in the form of a plug 31. In the example in FIG. 5, thecontact body is in the form of a socket 32 which is equipped with anannular contact lamination 33 of a known design in the interior.

If, in particular, cables having mechanically sensitive, fine-wire andvery fine-wire conductors are intended to be connected, it isrecommended to use a cable connection system as shown in FIG. 6. In theembodiment of the invention shown in FIG. 6, a clamping contour 20′ isused in the clamping sleeve 23, and this clamping contour 20′ in turncomprises two sections 20 a′ and 20 b′. The second section 20 b′corresponds to the section 20 b in FIG. 3. The first section 20 a′ has acontour which is slightly (convexly) rounded off and extends on averageapproximately parallel to the cone face of the clamping cone 21. Owingto the slightly rounded section, large-area clamping is achieved whichis “gentle” with respect to an edge and is suitable in particular forsensitive individual wires of the stranded wire 29. In this regard, theedgeless transition between the first section 20 a′ and the secondsection 20 b′ is also particularly favorable.

Overall, the invention provides a cable connection system which isdistinguished by the fact that

-   -   no special tool is required,    -   the screw connection can be released again, i.e. the clamping        screw connection can be reused,    -   it can be used up to the largest conductor cross sections        available on the market,    -   it is easy to manipulate, and    -   it can be used in a time-saving and thus cost-saving manner.

LIST OF REFERENCES

-   10 Socket-   11 Socket body-   12, 33 Contact lamination-   13 Spring bolt-   14 Perforated nut-   15 Compression spring-   16 O ring-   17, 17′, 25 Width across the flats-   18 Thread region-   19 Recess-   20, 20′ Clamping contour-   20 a, 20 b Section (clamping contour)-   20 a′, 20 b′ Section (clamping contour)-   21 Clamping cone-   22 Opening (funnel-shaped)-   23 Clamping sleeve-   24 viewing hole-   26 Clamping screw connection-   27 Marker recess-   28 Contact body-   29 Stranded wire-   30 Cable-   31 Plug-   32 Socket-   33 Axis-   W Clear width (clamping contour)

1. A cable connection system, comprising a contact body (11, 28, 31, 32)which has first means (18, . . . , 27) on a cable connecting side forthe purpose of producing a releasable electrical and mechanicalconnection with the end of a cable (30) and is designed on a contactside for the purpose of providing an electrical contact, in particular aplugging contact, the first means comprising an essentially rotationallysymmetrical, central clamping element (21), which is integrally formedon the contact body (11, 28, 31, 32) and tapers along an axis (33)towards the cable end, and a clamping sleeve (23) which concentricallysurrounds the clamping element (21), can be screwed to the contact body(11, 28, 31, 32) in the axial direction and has an inner, essentiallyrotationally symmetrical clamping contour (20; 20 a, 20 b; 20′; 20 a′,20 b′) such that, when the clamping sleeve (23) and the clamping element(21) are screwed together, a stranded wire (29), which is inserted intothe intermediate space between the clamping element (21) and theclamping contour (20; 20 a, 20 b; 20′, 20 a′, 20 b′), of a cable (30) tobe connected is clamped, characterized in that the clamping element isin the form of a clamping cone (21), in that the clamping contour (20,20′) comprises a first section (20 a, 20 a′) in which the limiting faceof the clamping contour (20, 20′) extends approximately parallel to thecone face of the clamping cone (21), and in that the clear width (w) ofthe clamping sleeve (23) in the region of the clamping contour (20, 20′)is smaller than the maximum outer diameter of the clamping cone (21). 2.The cable connection system as claimed in claim 1, characterized in thatthe limiting face of the clamping contour (20) in the first section (20a) extends parallel to the cone face of the clamping cone (21).
 3. Thecable connection system as claimed in claim 1, in that the limiting faceof the clamping contour (20′) has a slightly rounded section in thefirst section (20 a′).
 4. The cable connection system as claimed inclaim 1, wherein a thread region (18) is arranged on that side of theclamping cone (21) which faces away from the cable (30), for the purposeof screwing on the clamping sleeve (23), and in that a first recess (19)is provided between the thread region (18) and the clamping cone (21)for the purpose of accommodating the stranded wire (29).
 5. The cableconnection system as claimed in claim 1, wherein at least one viewinghole (24) is provided in the clamping sleeve (23), it being possible tovisually check the insertion of the stranded wire (29) into the clampingzone between the clamping cone (21) and the clamping contour (20, 20′)through said viewing hole (24).
 6. The cable connection system asclaimed in claim 5, wherein two opposite viewing holes (24) are providedin the clamping sleeve (23).
 7. The cable connection system as claimedin claim 1, wherein a marker recess (27) is arranged on that side of theclamping cone (21) which faces away from the cable (30), it beingnecessary for the clamping sleeve (23) to be screwed onto the contactbody (11, 28, 31, 32) up to this marker recess (27) before the strandedwire (29) of the cable (30) is inserted into the clamping zone betweenthe clamping cone (21) and the clamping contour (20, 20′).
 8. The cableconnection system as claimed in claim 1, wherein widths across the flats(17, 17′, 25) are provided on the contact body (11, 28, 31, 32) and onthe clamping sleeve (23) for the purpose of tightening the screwconnection with a defined torque.
 9. The cable connection system asclaimed in claim 1, wherein the contact body (11, 28, 31, 32) and theclamping sleeve (23) are produced from metal.
 10. The cable connectionsystem as claimed in claim 9, wherein the contact body (11, 28, 31, 32)and the clamping sleeve (23) are produced from brass and are providedwith a silver plating on the surface.
 11. The cable connection system asclaimed in claim 1, wherein the contact body is in the form of a socket(10, 32) or a plug (31) on the contact side.